How does a Holographic Projection Work?

Holograms. Images straight out of a fantasy world. But are these awe-inspiring holographic visuals all that they seem? In the futuristic sector of 3D technology, nothing ever is...

The holographic projection has been around since the 1940s, and while 3D technology has advanced quite rapidly since then, it still has considerable challenges to overcome to give us that “as-seen-in-the-movies” experience. However, some revolutionary 3D holographic pioneers are smashing boundaries in holographic projection and shattering the status quo when it comes to bringing holograms to life.

In this article, we’ll discover more about what holographic projection is, its relationship to holograms, and where the future of this technology is headed.

What is a hologram?

Before we travel to the future, let’s take a trip to the past and go back to the very beginning, so that we can find out just what a hologram is and ask ourselves,” what does “holographic” mean exactly”?

The term “hologram” was coined by Dennis Gabor in 1949, a Hungarian-born British electrical engineer and physicist, who later went on to win the Nobel Prize in Physics in 1971, for his work on the invention and development of the “holographic” method.

A hologram is a combination of two Greek words––“holos” meaning “whole,” and “gramma” meaning “message”; coming together to create a whole message, or in other words, a complete picture.

Unlike traditional photography, a hologram is a three-dimensional image or gives the impression of one. Created using light, sometimes in the form of lasers, there are a number of types of holographic techniques that present varying results.

What are holograms and where may you have seen them?

You have probably seen a hologram this week (if not today). That’s right. Holograms are all around us. Forget those science-fiction fantasies of Princess Leia pleading for help, the ones you’re likely to have come across are nowhere near as glamorous. However, they are extremely useful.

The holograms you may have seen are even closer to you than you think...in fact, they’re probably in your back pocket right now. Your credit card or driver’s license are perfect examples.

These holograms are created by splitting a laser beam into two separate beams, using an angled mirror. This then forms an object beam and a reflection beam. Heading in different directions, both are reflected off of other angled mirrors. The object beam is then reflected off of the object that will form the hologram image, and finally onto the end surface (also known as the holographic plate), while the reflection beam is directed straight onto the plate. As these two beams come together the hologram is created.

You may have also seen holograms in the form of product authentications, available on the back of many product packets. Simple and effective, although as we have begun to unpack above, the technology behind them is rather complex.

What other types of holograms are there?

Alongside the examples above, there are various types of holographic solutions out there. Here we’ll take a look at some of the most famous, focusing only on those that don’t require any additional accessories and can be seen with the naked eye.

The “Pepper’s Ghost” effect

Picture the scene. The year is 2012, the location, Coachella, one of the world’s most famous music festivals held in California. In the crowd, 80,000 fans are watching as rap icons Dr. Dre and Snoop Dogg take the stage.

Just as they end their set with “California Love,” originally performed by Dre and the legendary 2Pac, the stage goes black. Out of the darkness, a figure appears. There, standing right before the crowd is 2Pac himself. But how could this be? He died in 1996!

The deceased rapper that arrived on the stage at Coachella was, in fact, a 3D projection, created with a hologram effect. It was made using an old holographic technique called the “Pepper’s Ghost” effect and then updated to take center stage at this world-class music festival.

This is one way to recreate a ghostly holographic image, but, of course, it comes with its own challenges. Here are the pros and cons of this type of hologram.

Pros

• The “Pepper’s Ghost” effect can display large-scale projections, such as on the stage at Coachella or be as small as a shoebox, making it one of the most versatile holographic projection techniques.
• It creates a truly extraordinary effect, that when combined with the celebrity factor, has every capability of making international headlines.
• This is a well-established technique that has been tried and tested over many years.

Cons

• To create this illusion, you need a sufficient amount of plexiglass (placed at a 45º angle on the stage where you would like to display the holographic image), making the installation stagnant and heavy.
• It is dependent on light factors, meaning it is vital to ensure that the overall arena is dark enough to make the projection visible.
• Once you try to introduce other elements, such as Snoop Dogg in this case, the challenges only increase. The positioning and movements of the real-life elements need to be carefully planned and coordinated, so that the performer doesn’t come into contact with the glass or obscure the image in some way.

The Holographic Smokescreen

Similar to the “Pepper’s Ghost” effect, the holographic smokescreens work by using artificially generated smoke or a semi-transparent net as a “screen” for the hologram to be projected onto. Although, in this case, the projection comes from behind rather than below it. This creates that spectral image effect (a ghost-like projection) that gives the impression of a hologram.

The holographic smokescreen and net are widely used in the theatre when a specific scene calls for a spectral image, unlike the 2Pac projection, usually this type of holographic projection is designed to appear slightly translucent. Let’s take a quick look at the pros and cons of the holographic net technique.

Pros

• An effective technique for stage productions, as it creates a ghostly atmosphere and effect.
• Well-used and established as a theatre technique.

Cons

• Does not integrate well in the real world, as additional characters would be either left behind or in front of the semi-transparent net.
• When smoke is used other characters interrupt the effect, making the effect temperamental in terms of surrounding environmental factors, such as lights.

Holographic Nets

One of the latest technologies to enter the holographic world are holographic nets, an almost transparent curtain of LED lights that display images in a variety of colors. These LEDs are programmed to create images that present a 3D holographic effect.

Holographic nets have been used for everything, from small displays to covering buildings with colorful pictures. They provide optimal advertising opportunities for companies looking to display their brand in lights.

Pros

• Ability to create large-scale displays up to the size of a building.
• Provides flexibility in its application, can be used flat or curved.

Cons

• Although the final result is effective, it is an imitation of a 3D image.
• Not as immersive as other variants, as the viewer is always aware they are looking at a type of screen.

Holographic Spinning Mirror Technique

A simple, yet effective solution. The impression of a 3D image is given by placing a spinning mirror at an angle and projecting a high-speed video onto it, which is then reflected to form the display.

Developed in the University of Southern California (USC), the solution was designed as a new innovation in 3D holographic technology.

Pros

• Creates an effective optical illusion of a 3D hologram.
• Efficient in displaying a 3D version of a video to a specific scale.

Cons

• Introduced in 2007, this technology has seen very little development since then.
• It is limited in size to the device, which restricts its usage.

Semi-transparent OLED screens

In recent years, serious investment has been made into transparent OLED screens by some of the biggest names in electronics manufacturing. These new inventions feature a screen filled with organic light-emitting diodes which react to an electric current to form an image.

In terms of 3D effects, the result is a 2D image that appears to be 3D, creating the illusion of a hologram on the screen. However, it is possible that this could be the future of our living room TV experience and new advancement in the advertising world.

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Can you use Holographic Projection in yourbusiness?

Pros

• Very new to the market, the technology is still rapidly developing and new versions are imminent.
• Creates a contemporary way of displaying content and gives a little more flexibility.
• Provides a bright platform for displaying content.

Cons

• Images displayed are 2D illusions of 3D images.
• With a transparency level of +40% (meaning the image isn’t entirely see-through) some background will still be visible.

Holographic Pyramids

These popular holographic solutions come in two types: the DIY holographic pyramid that you can place on top of your smartphone or tablet at home, or the infinitely more professional constructed holographic cubes, also containing a pyramid alongside a screen, that are sold online by many retailers.

These hologram pyramids utilize reflection in a similar way to the “Pepper’s Ghost” effect, creating the appearance of a 3D hologram floating within a case. This type of imagery works due to the 45º positioning of the sides on the pyramid on the glass, giving the impression of a hologram reflected within.

While the technology is impressive, there are pros and cons for users.

Pros

• Creates a holographic illusion that makes the image on your screen appear as if it is a 3D hologram.
• This type of installation can be made professionally or recreated for home entertainment purposes using homemade constructions.

Cons

• Only works on a small-scale and is limited to the size of the enclosure, pyramid, and screen involved, current maximum size is around the size of a table.
• Results vary. Professional pyramids produce much more realistic results than DIY versions, which look more like a reflection rather than a 3D image. Such technology must remain inside the cube or pyramid, making it difficult to scale or transport, limiting its usage.